The objectives of the Registry of Experimental Cancers are the storage and retrieval of pathological material and data on cancers and other lesions of laboratory animals (primary rodents) and the use of such information for research and educational purposes. During the current year the Registry has acquired 3,896 single or group accessions reaching a total of 12,658 . A total of 74,062 records have been coded. During this year 44 investigators have come to the Registry for study and consultation on single or multiple visits. A 16th study set "Liver Tumors in Mice," was completed. Seventy-eight study sets were loaned to investigators throughout the world.